This invention relates to a spinneret plate for use in the production of filaments such as textile or industrial yarn from a molten polymer of fiber forming molecular weight. In particular this invention relates to a spinneret plate that may be used to produce a yarn containing filaments having widely different physical properties, i.e., elongation and tenacity; such a yarn may be processed in such a manner that the filaments in the yarn with lower elongation and tenacity break and yield a product having free ends, or such a yarn may be processed to yield a mixed shrinkage yarn. The spinneret plate may have capillaries of different cross-sectional size and shape. The spinneret plate must have capillaries of different length. (The term "capillary" as used herein means the aperture through the spinneret plate through which polymer passes during a spinning operation, and includes any counterbore. A counterbore often extends the major distance through the plate.)
It is known in the art to spin fibers from a spinneret plate having different shaped capillaries--for example see Bradley U.S. Pat. No. 4,110,965. Bradley also discloses breaking the weaker filaments in or subsequent to the stop of false twist texturing the yarn.
It is also known that yarn properties are affected by the spinning temperature at the spinning surface (extrusion face) of the spinneret. The present invention makes it possible to spin a yarn having filaments with different properties from a single spinneret without the use of elaborate heat exchange equipment to cool one group of capillaries but not another.